I agree with all the others but also (addressing the original question):
A trust is a separation of legal and beneficial ownership of property. In order for a trust to exist it has to relate to an item of property (called “certainty of subject”). That can be £10 , €10, a pound coin, a tennis racket or a parrot. The parrot need not be attached to the deed.
It can be created in a number of ways. One way is by trust deed but there is no absolute requirement that a trustee has to sign it. That is just common practice to avoid/reduce any factual doubts and therefore risk.
Finally, trust law is a fascinating area (many lawyers would disagree!) but, at the risk of sounding protectionist, please don’t start advising on trusts (or wills for that matter) unless you have a thorough understanding of the law and practice. A lot can and does go wrong. Trust law is now more liberal since the perpetuity rules have be been eased but the complexity of trust taxation has increased to fill the gap.